Why the Pentagon Wants to Use Blimps for Missile Defense

Two radar-toting airships will fly over the U.S. east coast this spring as a test of the JLENS system.

The Pentagon caused a stir this week by announcing plans to fly radar-carrying, 80-yard-long blimps in the skies above the Northeast United States this coming spring. It says this is part of a U.S. Army plan to use that technology as the eyes of a domestic defense system.

"Raytheon is conducting research and development that will enable the system to better protect Washington D.C and a large swath of the East Coast from cruise missiles and drones," the Pentagon says. The backstory is a little more nuanced than that. Here's what you need to know about this technology.

Why blimps, and why now?

The higher a radar sits, the more ground it can cover. And the farther away it is from the enemy, the lower the chances that enemy will be able to shoot it down or shield its targets. That's why the Air Force flies airplanes like the E-3A: airliner-sized jets that scan airspace from high altitudes. But flying airplanes costs a lot of money and you can't keep them in the air at all times, leaving gaps in coverage.

This explains why unmanned blimps are so alluring. They're many times cheaper to operate, according to Raytheon, which makes them. They can cover vast swaths of land: The ones being tested this coming spring will be tethered and flown at an altitude of 10,000 feet in the skies near Baltimore, and will scan an area from upstate New York down to North Carolina's Outer Banks and as far west as Ohio.

The blimps, or aerostats, work as a pair. One blimp carries radar to track the incoming missiles. The other carries precision radar, called a fire-control radar, to track the missiles and feed data that can help a Patriot missile battery or (more likely in the domestic United States) a fighter aircraft shoot it down.

Why the Army is in charge of a blimp test?

The craft's official name is the Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System (JLENS.) The important part here is "cruise missile defense." The U.S. has a lot of potential enemies with access to cruise missiles and short range missiles. The Army, with troops around the world in established or makeshift bases, needs warning if they are being targeted. Minutes of warning save lives.

But there are no cruise missiles parked off the coast of the United States, and missile defense for the homeland wasn't one of JLENS' original purposes. This test is all about proving the system can handle those threats, too, so it could be used to track drones, boats, and cars. (The blimps have no cameras.)

So do we really need missile defense blimps?

The proliferation of missiles in the Middle East and other parts of Asia is driving the need for missile warning and intercept systems to protect American and allied bases. But the homeland is not really in the crosshairs of short-range missiles, with two ocean-based exceptions: submarine-launched cruise missiles and missiles fired from converted, clandestine civilian ships. (Intercontinental ballistic missiles (ICBMs) remain the chief missile threat to the American homeland.)

The good news for the JLENS program is that these lighter-than-air radar units can spot more than missiles. They can detect aircraft, like those Russian bombers that occasionally push close to U.S. airspace. They could spot illegal or unregistered ships and tell the Coast Guard to intercept. If placed over the sparsely populated parts of the U.S. border, such blimps could help to catch smugglers' land vehicles and aircraft. It never hurts to have a good radar picture of what's coming in and out of the country.

With all that said, the blimp test happening this spring says more about the resiliency of defense programs than it does about emerging threats. After delays, unreliable results, and cost overruns, the project was cut back from 32 blimps (at $180 million each) to just two. One 2013 Pentagon report says, "The Joint Staff directed the JLENS program to deploy an orbit to Aberdeen Proving Grounds, Maryland, to participate in a three-year Northern Command homeland defense exercise from FY15 to FY17." That defense-speak explains this coming test: It's a last-ditch effort to prove the blimps were worth the effort.

Why do this this in the Northeast, where it must contend with so much airplane traffic?

That's the point of the test: to put the blimps into a real-world environment and see how they react. The busy airspace of the Northeast is a good place to test whether JLENS can detect, track, and discriminate a missile threat from the other objects on its radar returns. The system has had a hard time with this so far. The 2013 Pentagon report said that JLENS suffered from "non-cooperative target recognition, friendly aircraft identification capabilities, and target track consistency."

If JLENS can tell friend from foe in crowded Northeast airspace, then maybe it'll start to redeem its reputation inside the Pentagon.

A Part of Hearst Digital Media
Popular Mechanics participates in various affiliate marketing programs, which means we may get paid commissions on editorially chosen products purchased through our links to retailer sites.